PERFORMANCE EVALUATION OF sUAS EQUIPPED WITH VELODYNE HDL-32E LiDAR SENSOR

The Velodyne HDL-32E laser scanner is used more frequently as main mapping sensor in small commercial UASs. However, there is still little information about the actual accuracy of point clouds collected with such UASs. This work evaluates empirically the accuracy of the point cloud collected with such UAS. Accuracy assessment was conducted in four aspects: impact of sensors on theoretical point cloud accuracy, trajectory reconstruction quality, and internal and absolute point cloud accuracies. Theoretical point cloud accuracy was evaluated by calculating 3D position error knowing errors of used sensors. The quality of trajectory reconstruction was assessed by comparing position and attitude differences from forward and reverse EKF solution. Internal and absolute accuracies were evaluated by fitting planes to 8 point cloud samples extracted for planar surfaces. In addition, the absolute accuracy was also determined by calculating point 3D distances between LiDAR UAS and reference TLS point clouds. Test data consisted of point clouds collected in two separate flights performed over the same area. Executed experiments showed that in tested UAS, the trajectory reconstruction, especially attitude, has significant impact on point cloud accuracy. Estimated absolute accuracy of point clouds collected during both test flights was better than 10 cm, thus investigated UAS fits mapping-grade category

The Impact of Intense Exercise on Semen Quality

With expanding knowledge on the health benefits of exercise, there is an increasing demand for information on the andrological consequences of participating in sports. These consequences are especially important in the context of infertility problems worldwide. The so-called "male factor" is reported in up to 50% of couples having trouble with conception. The answer to the question, "Is physical activity good for male reproductive health?" is not straightforward. A number of studies have suggested that significant changes in semen parameters may occur due to sports training of certain types, intensities, and durations. The changes to these parameters vary in scope, direction, and magnitude. Findings in recreational athletes have also differed from those in professional athletes. This review of the current literature suggests that intense physical activity may affect the semen concentration, as well as the number of motile and morphologically normal spermatozoa. Training at higher intensities and with increased loads seems to be associated with more profound changes in semen quality. In recreational athletes, exercise has either a positive or neutral effect on semen parameters. Due to many limitations (e.g., global sperm count trends, concerns about the quality control of sperm evaluations, and new standards for semen analysis), comparisons among historical data and their interpretation are difficult

Multi-UAV Carrier Phase Differential GPS and Vision-based Sensing for High Accuracy Attitude Estimation

This paper presents a cooperative navigation technique which exploits relative vision-based sensing and carrier-phase differential GPS (CDGPS) among antennas embarked on different flying platforms, to provide accurate UAV attitude estimates in real time or in post-processing phase. It is assumed that all UAVs are under nominal GPS coverage. The logical architecture and the main algorithmic steps are highlighted, and the adopted CDGPS processing strategy is described. The experimental setup used to evaluate the proposed approach comprises two multi-rotors and two ground antennas, one of which is used as a benchmark for attitude accuracy estimation. Results from flight tests are presented in which the attitude solution obtained by integrating CDGPS and vision (CDGPS/Vision) measurements within and Extended Kalman Filter is compared with estimates provided by the onboard navigation system and with the results of a formerly developed code-based differential GPS (DGPS/Vision) approach. Benchmark-based analyses confirm that CDGPS/Vision approach outperforms both onboard navigation system and DGPS/Vision approach